Yes. In the past we took this approach in cases where estimates were not hard, ie. we knew the tech, the problem was not something new per se, and we were completely aware of potential third-party integrations.
If we already have a clear idea of how we could build your project, we can do it with a fixed scope, budget, and a precisely defined time-frame.
Many of our clients wanted to start this way. Usually, after the first project, they went on to work with us "our way" when we proved that we are truly committed to delivering desired results on time and that we, on a regular basis, exceed what was initially expected of us.
The only cases where we are always taking the "fixed scope" route is when we work with heavily regulated clients (like working with the Serbian government).